Electrophotographic printing processes, sometimes termed electrostatic printing processes, generally involve creating an image on a photoconductive surface, applying an ink having charged particles to the photoconductive surface, such that they selectively bind to the image, and then transferring the charged particles in the form of the image to a print substrate.
The photoconductive surface may be on a cylinder and is often termed a photo imaging plate (PIP). The photoconductive surface is selectively charged with a latent electrostatic image having image and background areas with different potentials. For example, an electrostatic ink composition including charged toner particles in a liquid carrier can be brought into contact with the selectively charged photoconductive surface. The charged toner particles adhere to the image areas of the latent image while the background areas remain clean. The developed image is then transferred from the photoconductive surface to a print substrate (e.g. paper). The developed image may be transferred from the photoconductive surface to a print substrate directly or, by being first transferred to an intermediate transfer member (ITM), which can be a soft swelling blanket, which is often heated to fuse the solid image and evaporate the liquid carrier, and then to the print substrate.
During the image transfer process, it is desirable that a developed image on an LEP ink transfer surface, such as the photoconductive surface or a surface of the ITM, is completely transferred from the surface to a print substrate, for example from a photoconductive surface to a print substrate via an ITM. However, during a printing process some of the developed image may not be completely transferred, leaving debris, such as fused LEP ink particles on a LEP ink transfer surface. Therefore, it can be necessary to remove debris, e.g. fused LEP ink particles, from an ink transfer surface, such as a photoconductive surface or an ITM. It may also be necessary to remove debris, e.g. LEP ink debris, from a surface of a LEP printing apparatus, such as a photoconductive surface, an ITM surface or a surface of a developer roller of an ink developer unit.
Some existing devices for removing debris from a LEP ink transfer surface, e.g. a photoconductive surface, employ a wetting roller to supply clean cleaning fluid to the surface and a sponge roller to remove debris and cleaning fluid from the surface. During the use of such existing devices, the sponge roller is squeezed following contact with the surface in order to attempt to remove cleaning fluid and debris from the sponge roller. It has been found that removal of debris from the sponge roller of some existing devices may be difficult and/or cause damage to the sponge roller. Incomplete removal of debris from the sponge roller, or damage to the sponge roller may lead to debris being deposited back on the LEP ink transfer surface which may cause degradation in print picture quality and/or damage to the LEP ink transfer surface.